STAMFORD -- A 68-year-old city man died following an accident probably caused by a medical emergency while driving on East Main Street, police said.

Sgt. Andrew Gallagher said two witnesses saw the man pull off Interstate 95 southbound at exit 9 at noon and stop his silver pickup truck for the red light before turning east on East Main. Before the man cleared the overpass, his vehicle appeared to be out of control, said Gallagher, who heads the Police Department's Collision Analysis and Reconstruction Squad.

The man's identity has not been released pending notification of his family, Gallagher said.

"The man proceeded eastbound on East Main Street, and as he was crossing over the bridge over I-95, the vehicle veered into the westbound lanes, mounted the sidewalk and struck the guardrail, and continued in the westbound lanes until it came down here and struck the building," Gallagher said.

Before striking the Dobson Irrigation building at 1228 E. Main St., the truck clipped at least one telephone pole, Gallagher said. Firefighters were working to shore up the Dobson building, which was seriously damaged in the accident.

"Preliminarily in our investigation and based upon the witness statements and some of the evidence here, we believe it was a medical episode," Gallagher said.

Irrigation company owner John Dobson said after the man's wife arrived at the scene, she told investigators that her husband was having serious heart problems.

"I believe he had a heart attack," said Dobson, while explaining what the man's wife said to police and firefighters at the scene. Gallagher said he would have to wait for medical reports before he could establish that as a cause.

Dobson said his employees were stunned by the crash.

"The girls upstairs thought a bomb hit the office when the truck hit the building."